Automatic telephone system.



CA S. WINSTON. Mmmm TELEPHONE sYsXEM APPUCATION HLEI) SEPT- 30| |912 A L1 970990, Patented Sept 12,1916.

3 SHEETS-SHEET 24 C. S.WH\1STUN` AUTOMATIC TELEPHONE SYSTEM. `Mmc/mou min swr. 3o. m12.

s SHEETS-SHEET s,

lutentedSept. l2, N16.

UNITED STATES PATENT OFFICE.

CHARLES S. WINSTON, OF CHICAGO, ILLINOIS, ASSIGNOR TO KELLOGG SWITCHBOABD AND SURPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

`Specification of Letters Patent.

Application @led September 30, 1912. Serial No. 723,013.

. provements in Automat-ic Telephone Sysa system as,disclosed in a tems, of which the following is a specification.

My inventlon relates to two-wire or metallic line automatic ltelephone systems in which automatic switchesknown as the twodimension type are employed, these switches comprising a bank of contacts divided into groups, and cooperating wipers adapted to receive a primary adjustment to select a group of contacts, and thereafter a secondary adjustment to select a contact in the selected group. I

My invention has to do more particularly with systems of the above character in which no slow-acting relays are employed in the adjustment and release control circuits of the direetively controlled selectors and connectors, an-object of my invention 'being to provide a system of the labove character havinga more simpltl circuit arrangement, positive in operation c: d easily maintained.

In metallic line automatic telephone systems hitherto employed, and in which twodimension switches are used, slow-acting secondary relays and release relays are employed in connection with a quick-acting primary or impulse relay in such airmanncr that during the operation of the primary relay, although the circuits for vthe, secondary and release relays are rapidly inten.

rupted, said relays due to theirjslu'ggish or slow-acting construction maintain their armature attracted until a prolonged interruption of their holding circuit. This required a specially constructed slow-acting relay and to overcome this I have provided previously filed application of mine, wherein standard quick-acting secondary and releaserelays are employed, and in which two energizing circuits are provided for said secondary and release relays for maintaining them energized and their armaturev attracted during the operation of the primary relay. My present application looks to an improvement in the manner in which these two holding circuits for the secondary and release relays are provided.

In my present invention I provide two energizing circuits for the release and secondary relays, the first or primary circuits including a source of 'current adapted to he closed through contacts on. the primary relay and a winding of the release and secondary relays, this primary or first circuit being of suflicient strength to energize the relays and attract their armatures. A` second circuit is then provided for each of the relays including a source of current of coinparatively low voltage and sufficient to maintain the armatures of these relays attracted while the primary circuit is being rapidly interrupted hy the impulse operations of the primary relay. When the primary circuit of either of these relays is interrupted for a prolonged period, the low voltage circuit is not. suiicient to maintain the armature in its attracted posit-ion whereby it restores to normal to bring about a circuit change.

For a. more complete understanding of my invention reference is to be had to the accompanyin'gf drawings, in which like reference characters indicate like parts, and in which Figure 1, comprising parts 1, 2 and 3, illustrates a so-called complete automatic telephone system; Fig. 2 illustrates diagrammatically a mechanical line switch adapted to operate in connection with line 'switch circuit B; Fig. 3 illustrates diagrammatically a contact bank andwiper arrangement employed in connection with the selector and connector switch circuits illustrated.

In Fig. 1, I have illustrated a soecalled 10,000 line automatic telephone system out have shown only suflicient apparatus for eX- tending a connection from a calling to a called substation. li-In the preferred embodiment of my invention I employ substations A, line switches B, first selectors C, second selectors D, and connectors E, a called substation F with its associated switch B1 also being illustrated. In a full installation of a system as referred to, there Patent-ed sept. 12, i916.

would be 10,000 substatiens A each Cong nected by a line L with its associated line switch B of which there would be 10,000. These lines'and switches B are divided into ten major groups or" 1,000 each, and each major group is divided into minor groups of 100'eaeh. 0n a basis of ten per cent. trunkingr there would be provided 1,000 first each each group o -10 being ed vizo n mindi" grup'of; 100 line switch selectors C, and to -this end' anonimi-'selectors C would belmultiple connected tothe 'buik contacts of-the associated 100 line' s fitxzhe's B. although in 1" ig. 1 butfwo suchinnltple m connections are shown.'

On, n b. 's of ten per cent. trunkingfus" previously referred to, vthe sele'etaoxandv con- .necor switches empio 1(1)()l sets ofbmkjimn.-v tac'ts J' (Fig. 3) divi ed intovtel'l 'groups of 15' t'cn contact sets each, und .the cope'r'tilig wiper set W may be primarily adjusted to select onejo-the groupso'rrows ofnonvtncts, and thereafter secondarily ndjusbed'ti select.

n contact set 'in a 'group j .Therefore o'n-the.-

29 basis outlined, .one thonsandfsecond seletois D would alsohe provided, beingdivided f' into I0() oups of ten seeondfselectorsech, n ndeuch nh group ofg'ten second selego'rs y DA would ,"have its wipers multipledhfore 25`the' bankpontactsfof 100` rstfselecorsC vTh each. suoli one hndredy selectors; vcomprising preferably tenl ggonpsjofgen first. Selectors' enh, these *en grQPSbeingi tho'comespondjg hundred or'minoi1-grou s.- laoof the ,te'njma'jor groups. In othelfmfor l.of these ten minos-.groups .would ox: imxjor group,l the second goxi A etc. Thus assumingn subscriber wgroup, the. first operiniiorrof .hisgllingdef connect; with. alinein the third 60 vice' would resulhntiuee prirngryfstepsfof i -sletorsfD m the third thoxisixiidgro are provded, i.divided vinto vone hunded employed iu thib embodiment ot' my invention, mhctationa A are. of the well known K loejgg type having a calling device l with it interruptor contacts 2 coef'iected in circuit with the line conductorsA the impulse wheel Z3 being' so arranged that when ad vanced7 its teeth willv not interrupt the contacts 2 hntupon being restored hy its spring it will interrupt said contacts 2 according to the number ot teeth on its periphery which were initially moved beyond said contacts. The line l; com liniaine line comiluctors t and 5 extend trom suhstation to itsI line switch B. Line switch B comprisehL a line relay lill cut-oiln relay (Y). motor magnet hl, oll ormai contacta ON, and a pair of line vipera l) and i? and ffoiii'ierating conta-trly orthcr with a test wiper 1G and eoiiperatif: contacts;

Fig. illustrates diagrammatically a .wit-ch mechaiusni adapted to operate in Connection with circuits B, like reference characters indicating corresponding parts. Thig Switch comprises Seta ot bank contacts' 17. 1Q., l!) and cooperating wipers 9, l2, 1G mounted upon a central shaft Carrying a ratchet wheel 6 adapted to he driven hy motor magnet M. It will be noted that two check pawla 7 and S are employed, paw] 7 heing normally in engagement with ratchet G while pawl Q normally out ot engagement with said ratchet. ln the preferred operation oi' Fig. L), which is in accordance with circuit B, upon initiation ot a call hy removal ot" the receiver from the switch hook` line relay LR is energized thus causin;r thc associateiil pawl S to engage ratchet wheel (i and thcicat'ter rut-oila relay C() is energized calming its associateftl ratchet 7 to disen'rgagze from ratchet wheel (5. Thereafter the motor magnet M advances the wipers over the contacts, followed hy the dcenerejimti:ai ot` UU; hut L1? is maintained energized so that hoih piwla` 7 and S an engaging ratchet C. To release Switch li line relay [dt n; deiinergized. thus withdra wing pawl S 'trom engagement with ratchet ti and thereafter cut-ott relay C() iS again energized movingr pawl 7 out of cen-- marmi-nt with ratchet it, allowing the wipers to he restored h.' a suitable spring. Un the first step oflnormal. contacts (.)N :reunie their alternate position and are maintained thus until the wipers are re- .-tored. whereby said contacts 0N are again moved to their normal position. Other forms ot line switches; may he employed 'without in any way effecting the principle or operation ot' my invention.

ln Fig. 3 l have illustrated diagrannnatially the contact haul( and wiper arrangement olr one torni oi selector and connector Switch that may he :ned with my invention. and tor a mori complete understaridingr of the witch estructura reference is to' he had to Iets in each group.

an application ot William Haisling for automatic switch Yfor telephone systems. Serial No. 304115134` liatent No. l.l3.ll0 tiled January 3rd. llll. Any Atorni of :switch adapted to :yelect a group ol contacts` and then an idle contact in the group.. would he equally within my invention.

My preferred switch7 referred to in the previous paragraphs (See Fig. $5) in general comprises a haut: ot' contacts (which lf have indicated inclosed in dotted lines). made u i ot' one hundred setfotl contacts, arranged in ten vertical groups J1, J2, dit, cto.` to JW, ten Each Set consists ot three contacn 4l, 42. t3. (which for clear illustration l have `"prend apart at the lirst row in Fig'. It and which correspond to contach,l Y11.412. and l?, in Fig. l. lart l). A set oie wipers 1V consisting ot' wipeu,` llt, 35 and flo are provided to wipe over the cfnresponct inL contarle in the vertical P rrouliaA (These wipers corrcapoud to wipers till. 35' and 36 in Fig. I lart lli A primary magnet (PM, hier l. lart il if; adapted to rotatetl'ie wipers through the medium ot' a primary sha'i't PS to hring them opposite one of the vertical groupe otl contacts. This group selecting` movement ia in response to directive impulsesI sent over the line from the, suhocrihers Station. it wcondary magnet, (SM. Fill; l. lvart, l). ir provided tostep the wipers in a vertical direction through the medium of a `araondary shaft to Select an idle contact et in the selected group. 'This aecondarv movennnt to select an idle set of contacta in the selected group in the Seleftftors is accomplished autonmtically. without the aid oi directive impulsesv troni the. suhsafrihcr's station. The awitch con struction is pret'ei'iahly arc advanced against the` tension ot a pair ot' fio-called watch springs. one springf opposing cach movement respectively.

To relcfm` the .awitch wiper#` and restore them to normal position after connection with one of the sets ot' contacts in a group`r the secondary magnet, is again actuated to step the wipers heyond the last or top contact ot that group. whereby they are auto lnatically restored to normal hiv the spring.`1 referred to` the wipers' in being reatored taking the path indicated hy arrows in Fig. 3. Thun. in the operation of the switch the contacting ends ot' the wiper` travel in a primary direction (horizontal rotary) to select a group ot' contacts`r then in a Secondary direction l vertical rotary) to select a contact in that group. and in the release ol the wipers this secondary travel continued until the contacting ends have passed heyond the hat or top contact in the group. when they are automatically released aS Shown hv the arrowa, to normal poenition.

act ot primar;Y ott-nomad sprintfy contach` 1)( iN are mm ed upon the that primarv such that the \.viper,-.

)to 'ne energized responsive to the step ol the switch while a set of secondary ntf-normal spring contacts SON are moved upon the first serondary step of the switch. being restored' 'upon restoration of the wipers trom their respective movementsy as will he clear from the diagram.

or imluifse rela;v Vb adapted to be erfrjgiz/.eil by current over a calling; imc n. eonmrtion made with said yswitch (l. a nf wiet relay MRR which i adapted it.

/l responsive te the iniqial c tion reiay Pit. a reieasciwlal." lti :uien of Mltl. am@ a secondari la); t it adapted to be energized toilo'w il the nuff ation of RR. test rela)l 'li i` atan prmided being adapted to he cncr to etici-t, a secondary travel oin they switch to schat an idle set of contaets in the selce 'l group.

Second selector l) (Wig. l. lart fi isy pret eralily the same construction as the tirst o lector. and compaises wipers and suitahle liant contacts. operating! magnets Ylill. Siil. a release relay RRI. and test rela)` Tli. Utinormal switches PUN and SO are also provided.

Cour-,ector switch li ot' the same consti m'- tion. comprises. besides its wipers and co operatn.r contacts. ofi-normal switches PHY and HUNT?. operating: masificfs Ei-lk. 54N. rrieasc relays lt i". till". itching rr lars fiiv' and SU". a lint tru rciay lit. .i relay il controlled by relajv li'l` and main tained energized while l'fl" is energfixed` a flip-flop or interrupter reia)v l"`l-` for inten mittently connectingr ringing generator tl and the bridged control relaiv t`l` across the terminals ot the called liuc. a disconnect rciaif Dit tor distamuet-tiney the ringing eurrcnt upon response ol. the erlled subscriber. a .'ireuit closingr relay tl, also energized hen a rallctl subscriber responds and a bus): and test, iutci'rupter relay Bil tor controlling the application ot a busy signal troni busy bachlli. and interrupting the terzi 1rcui' it the called liuc is busy.

'the called line lf. called substation lI and associated line switch l' are similar;` to the calling line equipment. the similar parts ben ing indicated by like reference characters hut with the suffix prime.

U/frfffio/l of ["z'g. l.mlla\'in;1 described in gem-ral the apparatus and circuit arrangement in the preferred embodiment of my invention the operation of' the system illustrated. in connecting: a calling' and called line. wili now be described.

through the winding of' LR, wiper 9, nor

mal contact 1U. line eonduetor 5, substation i\. line comlurtor Vf, normai contact 11,' the wiper lt! to ground. iteiay LR is thus energized #heine its alternate contact 13 and estal.ilishnqsr an energizing eircuitfor eut ofi' relai' tit) through normal contact ON. Relays liit and being energized. a circuit; tor motor magnety hl established through their alternate contacts IIJ: and 15 respectively. whereinv said magnet M advances wipers El. 1;' and lt into engagement with the first set ofl contacts li. We 1S. which, wc wii asL-inue. lead to a bus \v first selector t. yl`hcretorc. the test contant itl thereofis jrronnilcd through primary olf-normal Contacts l().\`. said contacts being in their alternate position when the selector C is busy.

and a locking circuit Jfor relays LR and C() 'therefore established which may be traced trom ground through lO contacts, wiper lt, and alternate contrufts 2t), 2l and the windings ot' relays LR and t() respectively. Relay t'() thus maintains the. eirrnit ot' driving magnet M closed notwithstanrlim Y the openingr ot the circuit at ottnormal contacts UN at the first step ot' the sw itch. Magnet M now :ulvances the wipers another step and in fact continues sneh ad-- raneement until the test iper lt reaches an idle fest contact ld which we will assume is the third on` leading to first selector C. `\.-1.timingthis is idle. as stated. it would be imgsroumed and therefore the locking circuit for relays Ll( and tl() is interrupted, but. rela)v Llt being' a slow relaymaintains its armature attracted until a locking cirv cuit f'roni switch (i is provided. which will bc later described. but relay C() beiner a quielercla)v innnediately releases its armature openingr its contact l5 in the circuit of driving magnet` M, thus renderin;r the switch wipers inert.

As above stated L is one of a group of lines that has access to a group of ten first selectors t". and thus the first idle selector C of' the group is automatically selected by the removal of the receiver from the hookof any one of said group of 10() lines.

l)ue to the closingY ot normal contacts 1G,

11 ot' relaiy when it is denergized, a`

circuit f'or the primar)Y relay PR of the Selector t is established over the calling line which may be traced from battery through the lett hand indiug of PR, the upper normal contact 23 of PON throughthelower winding of MRR to` battery, causingthe energization of li/IRR. Alternate contact Vof MRR is thereforegelosed and a second energizing circuit' for MRR. is closed through its upper winding, this circuit beingof a comparatively low voltage and sufli- .cient only to maintain the armature of MRR attractedjwhile the first circuit of vMRR is rapidly interrupted Aresponsive to the .impulse operations Aof primary relay PR. Also upon energization of MRR, its alten nate Contact 25,1 is lclosed establishing an energizing circuit for release relay RR whereby said relay is energized and its alternate contact 26 closed. W'iththe closing of thisalternatecontact 2 6, ground is connected from'alternate contact A251 through normal contact 27, .conductor 28. and the lower or first circuit vwinding of secondary VVVrelay SR, whereby said relay is energized.

Its alternate Contact 29 is l"therefore closed establishing a second circuit for SR through the upperor second'- 'winding thereof, this second circuit being of a comparatively lowA voltage-and adapted lto maintain the arma ture of SR attracted Nvliileits first circuitisl being rapidly interrupted by the impulse op-l erations of PR as will be referred to. Upon the energization of RR, its alternate con-v -tact 30 is closed'thereby connecting ground ,to contact spring 24, this ground being sub- 'stituted for `the ground from normal con- ,tact 23 which .will be interrupted upon the first primary step of the switch, while RR is maintained energized. Thus, it will be seen that upon connection made with first selector C its primary relay PR is operated followed by energi/.ation of 'MRR, RR, and SR iii succession.

Assuming the line with which connection is desired is No. 2343, the next step in the operation consists in operating calling device' -1 to cause two interruptions of impulse springs 2. These two interruptions cause two interruptions of the metallic energizing circuit of rely PR whereby it retracts and attracts its armature two times. vUpon the first retraction of PR and the consequent closing of its normal contact 24, an impulse of current is transmitted from grounded normal contact 24, through alternato contact 31, primary conductor P, branch conductor 2:31?, normal contact 53 aiidthe winding of PM to battery. Magnet PM attracts its armature and advances wipers 34, 35 a single primary step whereby primary Ott' lnormal switch PON is moved to its alternate position. Alternate contact 23 of PON is therefore-closed connecting ground to the test conta'ct 19 and rendering switch C busy until it is restored to normal; Also upon the movement of PON, its normal contact 27 is interrupted thereby interrupting momentai'ily the first energizingfcircuit o f SR, but

thev second circuit of SR is suilicient to maintain the armature` thereof attracted until the first circuit is a ain closed through alternate Contact 27 of P N and normal con#` tact 22 'of PR, which occurs upon denergi--v zation of PR. Also upon the firstand each succeeding loperation of PR, its alternate contactg24 is opened, interrupting the-first Y energizing circuit lfor MRR, but these rapid .v interruptions do not allow, the retraction of the armature of MRR -due to the VVsecond energizing circuit which is closed through alternate contact 25 of MRR `and the second winding thereof. The said two operations o PR` are effective totransmit two primary impulses through the winding of primary magnet PM'over the previously de- A scribed path resulting in two primary-steps of wipeis 34;, 3.5, 36 toA Vselect tliel"second grou-p of bank contactsl 41, 42 43 -which are contacts leading tosecond selectors'fin the second thousand group of-Ii'nes. l -g Following the last or secondoperation of PR, its normal contact 22, Vthrough which tlie first circuit of SR has be/'enclosed since the firstv primary lstep of the switch, is .in-g

terrupted for a prolonged period Awhereby the second circuit'of SR is notsuflicient to maintainv the armature attra'ctpcd, so` said armature 'restores closing normal Contact 291. The closing of normal Contact 29,l iselfec`` tive to transmit a. secondary impulse toca-use the operation of test relay TR Yand start the secondary travel of the switch. vThis secondary impulse l,may be' tracedfrom ground through the right end winding of PR, seconda-ry conductor S, normal contact 291, conductor 37, alternate Contact 38, nor,- mal Contact 39 and the winding of' TR to battery. Relay terrupting its normal contacts 46,5497 todis'- Connect the line wipers 35, 36 during' the secondary travel ofl the switch. v. T he closing of 'alternate Contact L10 establishes an ener# gizing circuit for SM, whereby the first im- TR therefore' encrgizes inpulse from` the connected alternating cur'- A 'trom said grounded-contact 41,wiper 34,

alternate contacts '44, 45, and lthe winding of TR to battery. Relay TR being main.- tained energized, magnet SM advances thc wipers 'another step and continues to adv'ance them until the wiper 34 reaches an ungrounded or idle test contact 4l. We will 'assume that' the third contact whichis con nected to second selector D illustrated is the first idle contact and therefore relay TR having its holdingI circuit interrupted is dcenergized interrupting the circuit for magnet SM. i

.Upon denerigization ofrelay TR, normal "contact 44 is closedl placing ground upon the multiple contactsP 41 connectedV to wiper 34, whereby an energizingcircuit'for relay RRl of Secondary selector D is established, traced over test conductor l61, normal contact 62, and the winding of RRl to'battery, causing its energization, whereby its alternate contact 63. establishes a locking circuit for it.

This ground potential at 44, .placed upon multiple contacts 41 also renders them unselectable by any other first selector. 'The subscriber at A now operates calling device l l to etfectthree interruptions of the rcircuit for relay R and responsive' to each ensuing denergization thereof its normal contact 24 is closed.. causing the transmission of threev primaryor directive impulses tothe Inaryrmagnfet PMl'of the selected switch D.

Responsive to'the'- first of said de'nergizations of PR., its noriual contact@ is again closedestablishing an initial energizingcir-V cuit for the secondary relay bl?. traced through al-ternatc'contact 27, conductor 28,

and 'the .lower winding of SR to battery. Relay. SR "again closes its alternate contact 29 whereby a second or alternate circuit for relay SR is closed through the upper winding of SR to the low voltage terminal of battery as previously described, The

y ond circuitfor SR is effective to maintain transmitted over `a path tracedA from the normal contact 24, alternate contact 3l, con- :pulses are coming `froinnormal contact ductor P, normal contact 4G, wiper 35, contact 42, th'e upper heavily marked primary conductor to conductor of switch l), normal contact .49 and winding of PMl to hattery resulting in three operations thereof. The wipers 50, 51, :i2 thcrcfoul receive {hr-rr primary steps to select thc third group oi contacts4 which are the contacts extending 'rupted at normal Contact "ondary step of the switclL lva net SM*v therefore continues to advance tie wipers.'

to connector switches in the third hundredths v group of the selected thousands group, and.

which includes the line of' the called Substation F.

Upon the first primary Step of switch D the primary-otlnormai contact 56 is closed so that upon the said retraction of the an mature of secondary relay SR.,- a' secondary7 Circuit is established traced from gro 'l through the 'right end winding of PR, i.. mal contact-"291, 47,'wiper 36, Contact the lower heavily marked seconc'lary con ductcz, alternate contact 56, normalcontact v 57 and the winding'o test relay TR.l to battery. Relay TR1-is thusenergized 'closing its alternate 'contact 58' whereby a circuit" for magnet SM is established causing it to Y i step the wipers into engagement-'with the first set of contacts in the' selected group. i

.Assuming this first set of contacts lead to a.

busy connector E, its test ecmtacx, 53 has busy or ground potential connected thereto (as will be pointed out) so that( a maintai' -V ing circuit for relay TR1 is established traced from said grounded contact 53, wiper 50, alternate contact 59,. alternate `contact 60 and the winding of TR:l to b'attery,fits initial .energizing'circuit having been inter 'Z onthe first Secuntil an idle set of contacts is Vreachedwhich.

we will assume are .the contacts shown con;

nected to connector. E, "and busy potential upon these cuitA V.for vrelay 'TRf interrupted causing its denergizatieri andv thel onsequent 'iuter-` wipers remain in engagementyvitlrthe con tacts leading to selected. switch AE'.

Contact 59 lis closed, placing .i ...105 Upon Adenergization; of TRlltsxrormai Y 'aground or busy potentialupon'ftliel seleceedtestcontact and'its multiples.rendering them un selectable. This goui'idconnection also is effective to cause ci of switch l?. its circuit bein Y traced over test gif/,ation ol relay ill'l'l.

- .,V z conductor G4', normal Contact ha and. theV winding f RRP' vto mttery, causing its energization. Upon said rcstnration of 'l its normall contacts (i6, E? bcingjagain closed, the circuit from the alling'line is extended through to .the connector, i

The subscribert A non' operates his ilingderice to effct foar operations of relay PR, this cornaponding to the thi-rd Vor tens' divit of thencalled lim.` mlnber; this resultin(1r nl the enel-'fixation or secondar" relav P t1 5 .A

SR in manner as before dcslfribcd and also it are transmitted four impulses oi" currez .through prim;

1.o 'iron` umm. med path icl ud selector l), no: (il, Contact S, cranio normalv contacts 69,70 and the winding of PM2 to battery causing-four operations thereof and four primary steps of wipers --7 72, 73, to select the fourth group of e'on- `as before described,` whereby a Secondary circuit is established including switching re-h -lay Sl-V of connector E. This circuit 1s traced from groundl through the rig-htend winding of PR along the lower heavily marked secondary conductor through switch D, conductor 77 Vextending from the second,

ary conductor ot'switchv E, alternate conl tact 7Sv (which is now closed), normal Conq. tacts 79, and'nthe winding of switching relay SV 'to battery. rfhis relay istherefore energized closing its alternate Contact SO` and establishing a looking circuitforv itself through normal Contact Sl torgrounded testiconductor (EL Alternate Contactl Si ofA relay SKV is also closed lthereby disconnect ing` the prima ry magnet PM2 and connecting the secondary magnet to the primary conductor.

'The subscriber 'at A-"now operates his dial to canse threeoperations `of primaryrelay PR, these operations corresponding in number to' the last or unit's digit of the called line number, 'whereby three impulses vare transmit-ted to. switch E followed by theA retraction lof the armature of SR in a manner as' previously -clesoribed The said last three impulses of current are traced over the previously vdescribed path including the' upper or heavily marked primary conductor to conductor (38 off switch E, alternate contact 82,-normal contact S3, the winding of SM2`to battery at normal contact 34. The.-

ensuing three operations of SM2 are effective to step wipers 71., 72, 73 into engagement withl the third 'set of contacts 74, 75, 76 which are theterniinals of the called line.

Following the transmission of the last so ries of impulses` secondary relay Slt retracts its armature in a manner as previously de) scribed to cffec'ta secondary circuit Vvchange, at v'switch E :by 'the application of ground through end windingr of. relay llt to the secondary conductor ot switch E- This ground connection then extends over ifon diictor :77, switch E, alternate contacts 7S, 79, normal contacts RS ai-ul the winding ot' switching,r relay SlVl to battery' causing Aits cnergization.` lts alternate Contact 81' is thereby closed establishing a lockingcir- Cuit for itself oi'erconductors SG, H7 to ground at alternate contact SS, lts normal contact 8l is also interrupted thereby interrupting the lockingr circuit for relay SlV causing its 'deiinergizatioir Also responsive to said energizatii-n of Sli" its alternate contact n is closed .to connect line test relay-LT in circuit with'tl'ie test Contact 74 of the seized line. This circuitis traced from wiper 71, alternate Contact 91 (relay BR" having been energized over a circuit ineluding normal contact 9() and alternate primary ott-normal Contact S8 upon the first oli'- normal' step of the switch), the lower u'inding of LT, conductor 9,7, alternate contacts 92, 90, conductors 86, ST-toground 'at alternate contact-SQ. Although the initial cnergizing circuit Vfor BR isj interrupted at normal contact 9() when .SlV isenergized,

B`R, being a slow-actingv relay, maintains its Contact 91 closed until al substitute energizing lcircuit for 'BR is established, pro-1 vidingthe calledffor' line isidle., as will he 'described Returning'now o relayZ-L'l, it will be notedthat its lower finding-has its terminals connected between 'ground at alternatecontact 91 'and the wiper 71.

Up to this period the operation of switch E is the same `whether connection has been made with an idle or a busy line but after this period tlie operation differs "depending upon whether the calledvline isiidle or busy.'-

or busy vpotentialnpon its testieontat 74, as indicated in Fifa-1, .Part 321s() that upon wiper 71 making donnectiontherewith and the circuit through the-lower winding of relay LT closed byV the-elosingofalterrnitel causing the energizalti'on of both relays LT- and CO1, the energization of CO1 removing,r

the. substation controlof its line switohB".

- Upon energization of'L-T, its alternate contact 93 is closed causing the'energzaton reistablishing an energizing circ'uit'for relayPR thus maintain-ingi its arn'iaiture attracted. .'lhe'closing,r of alternate contacts 95', 952, of` relay LTv shunts the, lower. winding thereof, but maintaining circuit. therefor".

is established from battery-'through its upper winding,r and the current reducing 'resistanceil, alternate contacts95, 9.5,- (,iouductor 97. alternate ia'intacts 92, 90, conductors Si", S7, to ground at alternater-contact SS.

This ground connection isalsoiextendcd.

through alternate contacts 952,91 [and .wi per 7l lo thecnragred terminal 7# nutnitaiuing Va diret-t, `roiuul upiurthis terminaliI and its multiples and thus rendering the associated line unsclcctahle by any other connector.-

Also` upon the closure of alternate contact il?) of LT, a path for current thx-ou h relay l `li` is established including condu .tor 9S; normal contact 99, the winding ofFF and called line isA idle there will 'be vno' ground of relay H whose alternate Contact Qtr-loses, i

interrupter l to battery. Bythe operation of interruptor l, relay FF is periodically energized thereby operating its conttcts 100,

101 to alternately connect generatorG and control relay CR in bridge of the terminals 75, 7G of the called line. Upon each connection of current from ringing generator the'call bell at substation F 1s operated, the circuit therefor being traced from the upperterminal of generator Gr, alternate Contact 100, wip' 72, terminal 75, over the line and through the condenser and call bell of station F, returning through terminal 70, wiper 73, conductor 102, alternate contact 101, to the lower terminal of generator G. y

Upon each retraction of the armature of FF, relay CR is connected in bridge of the called line, this circuit being traced from battery through the upper winding thereof, alternate contact 103, norma-l contact 100, to the terminal of the called line, while the other winding of CR is connected through alternate Contact 104, normal Contact 101, terminal 76'of the called line. .Due to the condenser included in circuit at the substation F while the receiver is on its switch hook, there is no path for direct current for relay (1R so that it does not energize until the called subscriber answers the call and removes l1is-reeeiver from its switch hook thereby providing a path for direct current.

rent through control rela CR is n'ovided s .V l

over the previously described path causing its cnergization. Therefore its alternate contact 105 is closed maintaining relay RR* energized as long as the receiver remains oli' the switch-hook at substation F. This prevents the release of switch E until the called subscriber replaces the receiver.4

`Returning now to (lll the closure of its alternate contact 100 is ctlective to prevent another application of ringing current to thc called line` also by the ensuing energization of relay tl. causing the establishment of a talking circuit by the closing of altern ate contacts 107, 10H. Responsive to said encrgization of (lL alternate contact 109 is closed establishing an energizing circuit for disconnect relay Dlt. which closes its alternate contact 110 establishing a locking circuit for it: elf over conductor S7 to' ground at alternate contact 8S. Relay DR therefore interrupts its normal contact 99 rendering relay FF inert and 1neventing any further application of ringing current to the terminals of the called line. The two substations are now connected over a conversational circuit including the heavily marked primary and secondary conductors, a condenser 111 being interposed in the primaryiconductor at first selector C while a condenser 1111 is interposed' in the secondary conductor at connector E, these condensers being connected in circuit to prevent interference between the control circuits of the respective substations.

.The talking battery for the calling substation is provided through the windings of relay PL, while talking battery for the called substation is provided through the winding of relay CR..

.liccaaa-After the subscribers have tinished conversation, by replacing their receivers upon their respective switch-hooksx they may clfect the release ofthe switches used in establishing the. connection. The release of the switches is preferably controlled from both substations, that is,` release of switches l, C, and D is effected when the calling subscriber replaces the receiver while the release ofthe connector E' is effected when the called subscriber replaces his receiver. This order of release may, of course, be varied.

Assuming now, that the subscriber at F replaces his receiver, the previously described circuit through relay UR is interrupted at the switch-hook of station F whereby said relay restores. Due to the interruption of alternate contact 10G of CR, relay CL is restored closing its normal contact 100 and thereby establishing an energizing circuit for release relay BH3 through alternate contacts 112 113. Relay RRi is therefore energized interrupting the circuit for RIF causing its restoration, but relay ltll is maintained energized through normal contact 1123 of RR: and normal contact NS to ground. The restoration of RR and consequent interruptionof its alternate contact 9; cll'ects the restoration of relays LT and and due to the interruption of alternate contact Jil of LT, relay llrestores disconnecting relay CR fromthe wipers and by the interruption of itsI alternate contact ill allows relay Bh to dciinergize.

Returning now to lili, due to the closing of its alternate contacts U3, Sl, magnet SM2 is counccted in circuit with the alternating current generator lll whereby the wipers are advanced in a secondary direction as already described causing their restoration and the restoration of the ott-normal contacts. vs soor. as contact .8S of PON2 restores to normal, relays S1' 71, BH3, and DR restore, as it will be remembered these relays were held energized over circuits includingr said grounded contact 8S., Upon restoration of RR its normal cont-act is again closed and as test conductor (il may still be grounded from second selector D, li R3 again becomes energized but this is .only incidental and has no effect upon the switch at this time.

The eut-ott' relay COl of switch Bl having been restored, the line of substation F is available for use in establishing other connections.

Upon the subscriber at A replacing his receiver, the circuit for relay PR is interrupted causing itsrestoration and the interruption of its alternate contact 24. Although the interruption of alternate contact 24 opens .the high voltage path for current through relay MRR, alternate contact 25 thereof being closed there is still a fiow of current through the second or low voltage path but this is not sufficient to maintain the armature of relay MRR attracted. Said armature therefore restores interrupting alternate contacts 25, 251 and thus allowing the release relay RR to restore.

Upon the closing of normal contact 45 of RR, a circuit for relay TR is established traced from battery through the winding of ,said relay, normal contact 45, alternate contact 27, normal contact 22 to ground. Relay TR therefore closes its alternate contact 40 effecting an operating circuit for magnet SM whereby the wipers are advanced to effect their release in a manner as previously described, also .causing the off-norma1 switches to be restored. Upon the interruption of alternate contact 27 of PON, the cir cuit for relay TR is interrupted causing its denergization and the interruption of the circuit for SM.

.It will be noted that upon the closing of normal contact 22 and the release operation just described, ground is connected through alternate contact 27, conductor 28, and the winding of SR to battery causing the energization of SR but this has no effect upon the releaserrof switch C as relay SR again restores when the alternate contact 27 of PON is interrupted.

Another incidental operation may occur when the calling subscriber replaces his receiver for release purposes, this beingr an application of ground over the primary conductor. This is brought about in the following manner. Upon restoration of PR its normal contact 24 closes, and as relay RR maintains its armature in an attracted position for an instant after restoration of PR, ground will be connected through alternate contact 30 of RR, normal contact 24, alternate contact 31 causing a short application of ground to the primary conductor. This incidental application of ground to the primary conductor in the present embodiment of my Invention, is effective to cause a primary step of connector E (if said connector was released by the called subscriber before the calling subscriber replaces his receiver) but ifsaid connector E is so operated, it is automatically restored. This incidental operation of connector E is brought about as follows: The ground im )ulse to the primary conductor follows a pat over conductor 68 whereby the locking circuit for RR1 of switch D is interrupted causing its restoration. A release circuit is thus closed for relay TR1 traced from ground at alternate contact 115 of PONEr normal contact 6() through winding of TR1 to battery. Its alternate contact 58 is thereby closed establishing an energizing circuit for SM whereby the wipers are advanced and the restoration of switch D effected in a manner as previously described. It will be noted that while switch D is restoring a ground or busy potential is connected to test conductor G1 due to the closing of normal contact 116 of relay RR1, this belng removed when alternate contact 62 of PON1 is interrupted. Switch D having been restored is available for use in establishing other connections.

Now as to the restoration of switch B, this is effected upon restoration of switch C due to the interruption of alternate contact 23 of PON, this bringing about the restoration of relay LR which has been held ener gized through this alternate contact 23. Upon restoration of LR its normal contact 13 is closed connecting ground through aln ternate contact ON and the winding of CO to battery. Thus relay LR being denelgized and relay CO energized, both retainlng pawls 7, 8 are disengaged from the ratchet 6 allowing the wipers to be restored. Upon restoration of contact ON the circuit fory CO is interrupted causing its denergi- Zation whereby switch B is at normal and available for use in extending other connec tions.

ConnectorlE it will be remembered was incidentally stepped one point off normal, and relay RRL thereof was energized over the circuit including the grounded test conductor 64. But, upon the removal of this ground due to the interruption of normal contact 55) of relay TR1. switch D. relay RR2 restores energizing relay RR3 and causing a restoring operation of switch ll from the incidental operation.

In the previous description of the release operation it was assumed that the subscriber at the called substation was the first to replace the receiver upon its switch hook. le will now trace the release operation under the assumption that the subscriber at the calling substation was the first to replace the receiver followed by the replacing of the receiver at the called substation. In such a case relay DR denergizes upon replacing llas.

' relay BR restores closing the receiver at substation A, causing a restoration of the switches C, B, and D in a manner as previously described. In this instance the connector switch is not affected because its release relay RR2 is energized over a path including grounded alternate Contact 105 of relay CR, said relay CR being maintained energized over the calling line. Therefore, when the subscriber at slibof alternate contact 106 of CR, relay CL restores to normal followed by the denergization of RR2, while due to the interruption of alternate contact 106 of CR, relay CL restores. Res onsive to the restoration of RR", relay R3 energizes closing a circuit through SM2 whereby the wipers are alitomatically restored in a manner as previously described. Also, upon restoration of RRZ, due to the interruption of its alternate contact 92, relays LT and CO1 restore, the restoration of alternate contact 93 of LT causing the restoration of relay H followed by the restoration of BR as before described. Upon restoration of PON 2, relays DR and SVV are restored whereby the switch being at normal is available for further use in establishing other connections.

The restoration of CO1 of line switch B1 restores the substation control of its line switch whereby the line is free to be used in establishing other connections.

Called line bus 1/.-In the previous description it was assumed that the called line w as idle upon connection made therewith. `lt will now be assumed that said line is a busy line upon connection being made therewith, in which case its test terminal 74 will have a ground or busy potential connected thereto either from alternate contact 131 of switch B1 if the line be calling, or from the grounded test wiper 71 connected to multiple of terminal 74 if the line be a called line.

It will be remembered that following the last secondary circuit change, relays RRZ, SW1 and BR were in an energized condition and the closing of alternate contact 91 of relay BR had connected the lower winding of line test relay LT in circuit between ground at alternate contact 88 of PON 2 and test wiper 71 and terminal 7.4. It will be remembered also that upon connection with the idle line, relay LT was energized, but in the present case there being round or busy potential upon test terminal 74, no enerizing circuit for LT of E is provided as oth of its terminals are connected to ground, and it remains inert. Therefore, relay H is not energized so that slow-acting its normal contact 117 connecting busy back BB1 through alternate contact and normal contact 82 to the primary conductor. This busy tone follows a path back over the rimary conductor and out through the receiver of the callingvsubstationA then back over the lower heavily marked primary conductor through the ri ht end winding of relay PR to ground. he subscriberl at A in response to this signal knows that the Wanted line is busy and therefore replaces his receiver upon its switch-hook interrupting the circuit for relay PR. Upon restoration of relay PR, switches C, D, and B are restored in a manner as previously described, and in the present instance switch E being olf-normal is also restored. This is brought about in the following manner. Upon the interruption of normal contact 59, relay TR1 of switch D, the energizing circuit for RR2 is interrupted (relay CR not having been energized) causing restoration of RR2 whereby its normal Contact 113 is closed connecting ground from alternate contact 88 through the winding of RR@l to battery. Relay RR3 closes its alternate contacts 83, 84 establishing an operating circuit for SM2 as before, whereby the wipers are advanced effecting the restoration of switch E in a manner as previously described. Upon interruption of alternate contact 88 relays RR"i and SWvll are restored and switch E being at normal is available for use in establishing other connections.

In connection with line switch B, means are provided to indicate to the calling subscriber when such switch has not been able to find an idle trunk. For instance if -all of the trunks leading -from contacts 17, 18, 19 are busy, their test contacts 19 will be grounded causing the switch to step to the last set of contacts 171, 181, 191. There being no ground connected to terminal 191, relay C() immediately denergizes but relay LR mainiins its armature attracted due to its slow acting construction so that upon the closing of normal contacts 10, 1-1 of CO, a locking circuit for LR is established from ground through busy back BB, terminal 181, wiper 12 over the calling line, returning to wiper 9, contact 171, contact 191, wiper 1G, alternate contact Q0, and winding` of LR to battery. A clmracteristic signal is thus transmitted from BB over the path just described whereby the subscriber at A l'eceiving such signal knows that all of thetrunks are busy and therefore replaces his receiver upon its switch-hook. The circuit for LR being thus interrupted, it restores to normal closing an energizing circuit for CO as be- Upon restoration i tot drawings. Also a number of batteries are shown in dilerentparts of the drawings but it is to be understood that these may be one and the same batteries, and those terminals which are shown connected to ground, in practice would be connected to the grounded terminal of the battery.

lVhile l. have embodied my invention in what is known as a complete automatic telephone system, it is apparent that my invention is by no means limited to such a system and furthermore while [have embodied it in circuits for controlling switches of certain characteristics, my invention is not limited to such particular switches. Also many changes and mmlificationsl will be apparent, and therefore l do not desire to be limited to the structure as shown and described but ailn to cover all that which comes within the spirit vand scope of the appended claims.

W hat I claim as new and desire to Secure by United States Letters Patent is:

l. A telephone System comprising a primary relay and metallic control circuit therefor, an automatic switch responsive to said primary relay, a quick-acting release relay and energizing circuit therefor including a, source of current a winding of said relay and a normally open contact of the primary relay, and asccond circuit for said release relay including a comparatively low voltage s-fiurce of current a second winding of said release relay and normally open. contacts thereof hereby said release. relay ma y maintain its armature attracted when its lirst circuit is interrupted by the primary relay for short periods only.

Q. A telephone system comprising a primary relay and metallic control circuit therefor, an automatic switch responsive, to said primary relay, a release relay and energizing circuit therefor including a source of current a winding of said rclay and a normally open contact of the primary relay, a second circuit for said release relay including a comfnu'atively low voltage source of continuous current supply a second winding ol said release relay and normally open contacts thereof whereby said release relay may maintain its armature attracted due to the continuous. tlow of current through its windings when its l'irst circuit is interrupted by the primary relay lor short periods only` and adapted to restore its armature responsive to a prolonged interruption ot' its first circuit, and release means for the switch rendered ctl'cctive upon such restoration of the release rmature Ii. A telephone system comprising a primary relay and metallic control circuit thcrclior. z i automatic switch responsive to '-,ad prinmrj. relay, a quick-acting secondary relay and cucrgiziiig circuit therefor includJ ing a wiudim.;` thczeot a source of current a normally open oll`-norrnal contact and a normally closed contact of the primary relay, and a second circuit for said secondary relay including a normall open contact thereof a second winding andy a comparatively low voltage source of current whereby said secondary relay may maintain its armature attracted when its first circuit is closed and interrupted by the primary relay for short periods only.

4. A telephone system comprising a primary relay andI metallic control circuit therefor, an automatic switch responsive to said primary relay, a quick-acting secondary relay and energizing circuit therefor including a winding thereof a source of current a normally open olf-normal contact and a normally closed contact of the primary relay, a second circuit for said secondary relay including,r a normally open contact thereof a second winding and a comparatively low voltage source ot' current whereby said secondary relay may maintain its armature attracted when its first circuit is closed and interrupted by the primary relay for short periods only, and adapted to restore its armature responsive to a prolonged interruption of its first circuit, and a secondary circuit change adapted to be etfected upon such restoration. l

5. A telephone system including an alitomatic switch, a source of current, a metallic control circuit for said switch including a primary relay energized by current over said metallic circuit and. responsive to rapid interruptions thereof, a quick-acting release relay having an energizing circuit closed responsive to the initial energization of the primary relay and interrupted responsive to said primary relay operations, a second energizing circuit for said release relay including a' normally open contact thereof a second winding thereof and a comparatively low voltage source of continuous current supply whereby said second circuit is closed and held closed only during said rapid interruptions ot' the first said circuit of the release relay to maintain the armature of the release relay attractcd..and operating and release means for said switch controlled by said primary and release relays.

(l. A telephone system including an automatic switch, a source of current a metallic control circuit. for said switch including a primary relay energized by current over said metallic circuit and responsive to rapid interruptions thereof, primary driving mechanism for said switch responsive to said primary relay release, a prick-acting Secondary relay havingI a lirst energizing circuit closed responsive to said primary relay and interrupted responsive to said primary relay operations, a second energizing circuit for said secondary relay including a normally open contact a second winding thereof and a compa ratively low voltage source of continuous current supply whereby said second circuit is closed during said interruptions of its firstcircuit and lts armature maintained attracted only during such rapid interruptions, said armature being retracted upon cessation of said primary relay operations to effect a secondary circuit change for said switch,

7. A telephone system comprising a primary relay and metallic control circuit therefor, an automatic switch, a release relay and secondary relay, an energizing circuit for said release relay including normally open contacts of the primary relay, an energizing lcircuit, for said secondary relay including a normally closed contact of the primary relay, whereby said release and secondary relays have their said circuits interrupted during the operations of the primary relay, and a second circuit for the release relay and the secondary relay including a second winding on each relay and a comparatively low voltage source-of current,

- and means for holding it closed while said primary relay is rapidly operating to maintain the armatures of the release and secondary relays attracted during the interruptions o ftheir first said circuits.

8. An automatic switch comprising a primary relay, a release relay, a quick-acting secondary relay, an energizing circuit for said release relay including a normally open contact of' said primary relay and a source of current, an energizing circuit for said secondary relay including a normally closed contact of said primary rela 7 a normally open off-normal contact and said source of current, and a local circuit vfor each of said release and secondary relays including a comparatively low voltage source of current and normally open contacts of said relays whereby when said relays are energized they maintain their armatures attracted during the rapid operations-of the primary relay.

9. In combination with a primary relay and control circuit therefor, of a selector switch responsive to rapid operations thereof,a release relay and energizing circuit therefor including a winding of said relay nd a normally openacontact of the primary iielay, and a second energizing circuit for said release relay including a second windiing thereof and a source of direct current and of itself not suiiicient to maintain the armature thereof attr/ac/ted but whereby said release relay maintains its armature attracted when its first circuit is being rap/idly inferrupted by operations of the primary reay, said release relay being adapted to restore its armature responsive to a prolonged interruption of its first said energizing circuit, and release memslfpr said` switcgh eontrolled by said release re ly.

10. In combination with a primary relay and control circuit therefor, of a selector switch responsive to rapid operations thereof, a secondary relay and energizing circuit therefor including a winding thereof a nor- `mally open off-normal contact and a norstore its armature responsive to a prolonged interruption of its first circuit, and a secondary circuit closed responsive to such retraction of the secondary armature.

11. In combination with a primary relay and control circuit therefor, of a selector switch responsive to rapid operations thereof, a release relay and an energizing circuit for said release relay including normally open contacts of the primary relay, an energizing circuit for the secondary relay including normally closed contacts of the primary relay, whereby said release and secondary relays have their said energizing circuits interrupted during the operations of the primary relay, and a second energizing circuit for each of said release and secondary ond winding of each and a source of direct current of themselves not sufficient to vmaintain the armatures of the last said relays attracted but whereby said release and secondary relay armatures are maintained attracted when their first energizing circuits are being rapidly interrupted by operations of the primary relay, said secondary relay being adapted to retract its armature responsive to a prolonged energization of the primary relay following the rapid operations thereof to bring about a secondary operation of the switch, and said release relay being adapted to retract its armature following a prolonged denergization of the primary relay to bring about the release of the switch. l

12. A telephone system including an auto` matic switch, a metallic control circuit for said switch including a primary relay energized over said metalh'c circuit and responsive to rapid interruptions thereof, a secondary relay provided with a pair of windings, a comparatively low voltage source of current or sup lying current to one of said windings an a second source of current for supplying current to the other of said windings, means for closing an energizing circuit throu h the second of said `windings, said circuit being rapidlyi-Iiterrupted responsive to'said primary relay operations, meansT for closing a circuit through relays including a sec a secondary relay,

fliet-et of said windings for holding Said secondary relay energized during the period of said interruptions of its other circuit sn as to :maintain the armature or" aaiil ser ondnry relay attracted.

i3, A. telephone system inclufling :in aim matic switrli, a metallic eonrrol ciw-uit for :mid swieil including n minuit-y relay ensz gine-l over said metallic i1 :uit arel re sponsire to rapid interruption@ thereof.; a secondary relay `provided with a pair of windings, a comparatively l low voltage eonrnc oli-current for @implying current zo one of ,miel windings and L second source or' f fiirrcnl. for snnplying -zfizrrent lo the other ot' said winilingsi, means fl'ir dosing an enery fixing rireliit tllr'm wenn said winding :y :iaizl ein; it laying; rapidi inte;- :ngueil reg'mnsire in nifl priumry i my or eratione, inem.: tmrlofng a circuit through the tiret of said windings for holding said seconda ry relay energizen during the period of bairl interruptions of its other circuit so nrto maintain the armz'atnre of said second relay attracted, and a seoondary circuit cloeeil responsive to ille retraction of the Seroi'ulany arniatnre li. A telephone system including an auton matic switch5 n metallic control circuit for said switch including a primary relay energized over said metallic circuit and responeire to rapid interrnpniona thereof, a. release relay provided with :i pair or" windings7 a comi'iaratirely low voltage source of current for supplying current; in one of Said winilings and a :second source of Current for supplying vnrrent to the. other of amid windingy means for rlosingf energizing cirA 'snit ilirfmgli the eer-,omi .Y :ill winflingm siaifl ifm-nit being rapidly :ziieiiliplrcl il:

lift

sponsive to said primari4 relay operations, means for closing a cica-mt through the firm of saidnwiniings for holding said rrlemlr relay merel/wl .l fing? Lin gwiod of mail interrnptione` cirunit so f. in maintain il; mi roleaff i' .i for sair! control. l r mfl releaf relay,

li. i-ulaiww system including :1^ inutil, .Lfo'iirlr :i metnillc rou/(rol cirrfni. if said .awin'h including a primary relay enen gizcrl over raid metalli(- eircuit. and re spez to rapid intcrrnptinne thereof. a relezna) relai' anal a secondary elayMr an rmer l; :ing circuit for said releaae. ielay indu-ul infy normally open coi'ituets of the primary :may an energizing circuit tor the sec fzfnalary relay including normally closed coni of the primary relay, a second enerng circuit for each of the release and sec ondzu'y relays includinv a second winding of each and a source o comparatively low voltage ,direct Current, the said Second windof the release and secondary relay proriding means for holding their respective armatures attracted during the interruptions of their first circuit@` by ille operation of the primary relay, means for denergizing the said secondary relay to bring aboutv a secondary operation of the switch, und means for denergizin the said release relay to bring about a re ease.

Signed by me at ChicagoLcounty of Cook and State of Illinois in the presence of two. witnesses.

CHARLES s. WINsToN.-

Wi tnesses M. R. Roonronn, Groane Et Mmmen. 

